added iexplore.html

TODO: redirect for IE users only
fixed whitespace
adjusted font size and line height
renamed folder
modified blog posts; revised scripts
started evaluation portfolio
added SVG icon file

TODO: figure out how to use CSS styles with SVG
added CSS to SVG
updated geometry unit overview
added simple events to prob-stats objective

TODO: objectives for compound events, histograms
finalized prob-stats unit overview
updated unit 5 and 6 overviews
Merge branch 'iexplore' into edu
Merge branch 'blog' into edu
Merge branch 'masthead' into edu